Allow turkey to come to room temperature for an hour before baking.
Preheat oven to 325°F
Combine the rosemary, thyme, sage, salt, and pepper in a medium size bowl.
Peel and cut your onion into quarters. Quarter your lemon as well.
Remove turkey from packaging. Remove the neck and giblets, which if they are included with your turkey, will be located in the body cavity and stuffed in the next cavity. Sometimes skin will be covering the neck cavity and you just need to pull that out and the giblets will be in there.
Pat the outside of the turkey dry and remove the trussing around the legs (usually a bit of plastic).
Place all the seasoning mixture inside the turkey cavity, then place your quartered onion and lemon inside the cavity as well. I like to just scoop up handfuls of the mixture and then stick my hand into the cavity and spread the mixture around.
Gently separate the skin from the breast by lifting up on the skin and then pushing your hand in between the skin and muscle.
Rub about ⅓ of the herb butter under the skin.
Rub the remaining butter over the outside of the turkey. Making sure to get the drumsticks and wings.